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Controllable Soft Template For The Synthesis Of Gold Nanoparticles

Posted on:2008-01-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:C R WangFull Text:PDF
GTID:1101360218452943Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
At present, nanotechnology is the pioneering research fields and controllable synthesis of nanoparticles with special size and morphology is one of the most important components. It is well known that nanomaterials are different from the conventional materials due to the size, morphology, and the atom ratio of surface and bulk phase of particles, etc, and are widely and significantly used in such fields as photonics, microelectronics, magnetism, catalytic properties and biology. The formation of nanostructures is a new cross-field of colloid and interface chemistry and material science and also is one of the most active research fields.The characteristics of soft clusters composed of surfactant sodium dodecyl sulfate (SDS) and polyethyleneglycols (PEG) or polyvinylpyrrolidone (PVP) adding HAuCl4 were studied. Sphereial gold nanoparticles were synthesized in the soft template of SDS-PEG with the assistant of ultrasound and UV. Gold nanoplates, nanorings and nanoarcs were also synthesized in SDS-PEG soft template, but no metal hard template or extra reducer was needed and HAuCl4 was self-reduced by PEG component in the soft template. Multipod-like gold nanoparicles were then synthesized through reducing HAuCl4 by sodium citrate in the soft template composed of SDS-PVP clusters assisted by microwave irradiation. The effect of soft template for gold nanoparticles was studied. In a word, there are main four parts below:The first one includes in the critical concentration, specific saturation capacity of clusterization ([Γ∞]), aggregation number of bound micelle (Nb), polarity of microenvironment (I1/I3) and hydrodynamic radius distribution (Rh) of SDS-PEG or SDS-PVP system effected by HAuCl4, which were studied by means of surface tension, steady-state fluorescence quenching, fluorescent molecule probe and laser light scattering. It is found that HAuCl4 reduced the first critical concentration (c1), had no effect on the second critical concentration (c2), increased Nb, and decreased I1/I3 of SDS-PEG or SDS-PVP system. With the increase of SDS in solution, Rh increased when HAuCl4 in n SDS-PEG or SDS-PVP system.The second one is that gold nanoparticles of different diameters were synthesized in a soft template of SDS-PEG with the assistant of ultrasound and UV. The concentrations of PEG (cPEG) and SDS (cSDS) were found to have a dramatic influence on the formation of gold nanoparticles. At a certain concentration of PEG, when the concentration of SDS is low, the more the SDS was in solution, the smaller the diameter of gold nanoparticles was. When cSDS was too high there were anisotropic particles such as triangle or truncated triangle formed in solution. When cPEG was higher the distribution of gold nanoparticles was narrow.The third one studied the effect of SDS-PEG template on the size and morphology of gold nanostructures which were self-reduced by PEG component in the soft template and no extra reducer was needed. HAuCl4 formed gold quantum dots, and then these gold quantum dots self-assembled to construct quantum wells, for example, nanoplates. These gold nanoplates were aged in their mother solution in different reduction periods and turned into ring-like structures, and eventually were splited into nanoarcs. Here PEG played the roles of both the reducer for HAuCl4 and the stabilizer for fresh gold nanoparticles. SDS and PEG together controlled the size and morphology of gold nanoparticles.The last part is to synthesize multipod-like gold nanoparticles with equivalent diameter around 50 nm through reducing HAuCl4 by sodium citrate in the soft template composed of SDS-PVP clusters assisted by microwave irradiation. It is found that the concentration of SDS and PVP effected on the morphology of gold nanoparticles. The shape the gold nanoparticles changed from sphere to multipod, then to sphere again when the concentration of SDS increased.
Keywords/Search Tags:soft template, gold, nanoparticle, sodium dodecyl sulfate, polyethyleneglycols, polyvinylpyrrolidone
PDF Full Text Request
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